Electromechanical disc adder mechanisms

ABSTRACT

An electromechanical adder mechanism for selectively influencing the operation of sewing machine stitch forming instrumentalities in accordance with a preselected pattern and comprising a plurality of discs which are arranged coaxially on a drive shaft including discs keyed to the drive shaft and freely journaled discs frictionally coupled to turn with the keyed discs. Axial cam segments on adjacent keyed and freely journaled discs may be selectively brought into engagement by electromagnetically influenced stop means for changing the angular orientation of the freely journaled discs relative to the keyed discs thus selectively to regulate the total axial dimension of the stack of discs on the shaft which is the output of the adder mechanism.

United States Patent 1191 Ketterer 1 ELECTROMECHANICAL DISC ADDER MECHANISMS [75] Inventor: Stanley J. Ketterer, Jamesburg, NJ.

[73] Assignee: The Singer Company, New York,

[22] Filed: July 16, 1973 [21] Appl. No.: 379,535

52 us. C1. 74/56, 112/158 D [51] Int. Cl. F16h 25/12 [58] Field of Search 74/56, 568; 112/158 A, 112/158 B, 158 D; 235/61 PA; 33/18 B, 23 J [56] References Cited UNITED STATES PATENTS 125,394 4/1872 Humphrey 112/158 B 767,480 8/1904 Hogan 112/158 B 2,086,523 7/1937 Burdette et al. 33/18 B 2,747,417 5/1956 Brown 74/56 2,917,591 12/1959 Juhas 74/568 T 3,055,325 9/1962 Adler 112/158 A 3,062,164 11/1962 Shimada 112/158 A 3,690,011 9/1972 Burchell 33/18 B FORElGN PATENTS OR APPLICATIONS 45-16974 6/1970 Japan 112/158 A May 28, 1974 Primary Examiner-Samuel Scott Assistant Examiner-Wesley S. Ratliff, Jr.

Attorney, Agent, or FirmMarshall J. Breen; Chester A. Williams, Jr.; Robert E. Smith 5 7 ABSTRACT An electromechanical adder mechanism for selectively influencing the operation of sewing machine stitch forming instrumentalities in accordance with a preselected pattern and comprising a plurality of discs which are arranged coaxially on a drive shaft including discs keyed to the drive shaft and freely journaled discs frictionally coupled to turn with the keyed discs. Axial cam segments on adjacent keyed and freely journaled discs may be selectively brought into engagement by electromagnetically influenced stop means for changing the angular orientation of the freely journaled discs relative to the keyed discs thus selectively to regulate the total axial dimension of the stack of discs on the shaft which is the output of the adder mechanism.

10 Claims, 13 Drawing Figures ELECTROMECHANICAL DISC ADDER MECHANISMS BACKGROUND OF THE INVENTION A variety of electromechanical devices have been proposed heretofor for translating electrical pattern signals into movements of stitch forming instrumentalities to produce predetermined stitch patterns. In varying degrees, all of the previously proposed actuators have presented shortcomings in one or more of a number of basic areas. First, they have been catagorized by complexity and delicacy of the parts which introduce problems of dependability and of wear and tolerance accumulation adversely affecting the fidelity of the output. Second, they have imposed severely critical time requirements as to the application of the electrical signals and as to the translation of such signals into mechanical output by the actuator which has worked to limit the practical speed of operation. Third, the electromagnetic devices in prior adder mechanisms have been required to develop forces which are related to the magnitude of the output force applied by the actuator. This requirement has made necessary the use of electromagnets which are large enough to accommodate peak output loads with resulting high noise, vibration, and wear characteristics in the prior actuators.

SUMMARY OF THE INVENTION It is an object of this invention to provide a sturdy electromechanical actuator construction with a minimum of critical wear surfaces which might adversely influence the fidelity of the actuator. This object is attained by the provision of a series of discs on a circularly moving drive shaft alternately keyed to and freely joumaled on the shaft with axial cam surfaces acting between the discs to influence the axial dimension of the entire stack of discs. Angular changes which are made in the position of the freely joumaled discs with respect to the keyed discs influencing changes in the output of the adder as represented by the total axial dimension of the stack. Relative movement is required between the discs only to reflect a change in the output and at all other times the discs turn as a unit and thus minimize wear between the parts. I

Another object of this invention is to provide an electromechanical adder mechanism in which greatly increased time is available for receipt and utilization of the electrical pattern signals. This object is attained by an arrangement whereby the pattern signal for a particular stitch is received and manipulated while a stitch in the pattern is being formed in accordance with the previously introduced pattern information.

Still another object of this invention is to provide an electromechanical adder mechanism in which the pattern information received as input to the electromagnetic device is unrelated to the magnitude of forces required to be delivered by the output of the adder mechanism. This object of the invention is attained by an arrangement of interrupter elements for influencing the relative angular orientation of stacked discs on the drive shaft in which the forces required by the pattern input signals are applied to the interrupter elements in a direction substantially perpendicular to the direction to which the interrupter elements assume the operating forces incident to the development of the output of the adder mechanism.

DESCRIPTION OF THE DRAWINGS With the above and additional objects of this invention, as will be apparent from the following specification, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a front perspective view of the adder mechanism of this invention as applied to the needle jogging mechanism of a sewing machine,

FIG. 2 is an elevational view of a portion of the adder mechanism of this invention showing one set of discs in a position adding an increment to the axial dimension of the stack and another set of discs in a position subtracting an increment,

FIG. 3A is a perspective view showing one side of a keyed disc of this invention,

FIG. 3B is a perspective view showing the other side of a keyed disc of this invention,

FIG. 4A is a perspective view showing one side of a freely joumaled disc of this invention,

FIG. 4B is a perspective view showing the other side of a freely journaled disc of this invention,

FIG. 5 represents a cross sectional view taken transversely of the drive shaft of the adder mechanism of FIG. 1 showing the keyed and freely joumaled discs in one relative angular position and showing the fragment of the interrupter element in a preferred position for initiation of electromagnetic influence by a pattern signal,

FIG. 6 is a view similar to FIG. 5 but showing the po sition of parts after approximately one-half revolution of the drive shaft when the interrupter element makes initial contact with a stop abutment on the freely journaled disc and begins to influence the relative angular orientation of keyed and freely joumaled discs,

FIG. 6A is an exploded perspective view of a set of adjacent keyed and freely joumaled discs together with the interrupter element in the position of parts illustrated in FIG. 6,

FIG. 7 is a view similar to FIG. 5 but illustrating that relative position of parts when the interrupter element conpletes that influence of the angular position of the freely joumaled discs which was begun in FIG. 6,

FIG. 8 is a view similar to FIG. 7 but showing the position of parts when the interrupter element makes initial contact with the second stop abutment on the freely joumaled disc,

FIG. 8A is an exploded perspective view of a set of adjacent keyed and freely joumaled discs together with the interrupter element in the position of parts illustrated in FIG. 8, and

FIG. 9 is a view similar to FIG. 8 but illustrating the position of parts when the interrupter element completes that influence of the angular position of the freely joumaled disc which was begun by engagement with the second stop abutment as shown in FIGS.

DESCRIPTION OF THE INVENTION Illustrated in FIG. 1 is an adaptation of an electromechanical disc adder of this invention indicated generally as 20 in a sewing machine bracket arm 21'shown operatively connected to influence the lateral jogging or bight movements of a sewing machine needle 22 in the formation of a pattern of stitches.

The needle 22 is carried by a needle bar 23 journaled for endwise reciprocation in a gate 24 which is pivotally mounted for lateral swinging movement in the bracket arm. An arm shaft 25 in the bracket arm may be connected by any conventional means (not shown) to impart endwise reciprocation to the needle bar. The needle bar gate 24 is shifted laterally to impart zigzag movements to the needle by means of a link 26 pivoted as at 27 to the gate and pivoted at 28 to a follower lever 29 fulcrumed at 30 in the bracket arm and having a roller 31 journaled at its free extremity. A spring 32may be arranged between the link 26 and the bracket arm of the sewing machine frame to urge the roller 31 to the right as viewed in FIG. 1 against the disc adder.

Also as shown in FIG. 1 is an assembled electromechanical disc adder of this invention illustrating that the parts may be assembled directly on an actuating shaft of the sewing machine such as the arm shaft 25 requiring only that the shaft be formed with a keyway 40 or its equivalent. Assembled in coaxially stacked relation on the arm shaft are a series of alternated keyed discs 50 andfreely joumaled discs 60. All of the discs keyed and freely journaled are axially shiftable along the arm shaft with the exception of the first keyed disc 50 which is formed with an integral collar 70 secured by set screws 71 fast on the arm shaft.

FIGS. 3A and 3B illustrate opposite sides of a typical keyed disc 50 showing that it is formed with a shaft accommodating bore 72 into which projects a key 73 for engagement with the shaft keyway 40. One side of each keyed disc as shown in FIG. 3B, is formed with an axially recessed groove 74, bounded by an internal control cam surface 75 and by an external control cam surface 76. Preferably the control cam surfaces 75 and 76 are circular but each having a different axis, both axes being located eccentrically from the axis of the bore 72.

-As shown in FIGS. 33 and to 9, the control cam surfaces 75 and 76 together define a varying shape for the groove 74 which includes a narrow segment 77 and a wide segment '78 for a purpose which will be described below.

Internally of the groove 74 the keyed disc is formed with an axially enlarged hub portion 79, i.e., the hub portion 79 is made thicker axially of the outer periphery of the disc.

The opposite side of each keyed disc, as shown in FIG. 3A is formed radially outward from the bore 72 with an axially extending cam segment 80 joined at each side by an arcuate and sloping ramp 81 merging smoothly with the axial cam segment 80 and with the face 82 of the keyed disc. It is pointed out that each of disc than the the keyed cam discs are identical with one exception, i.e., the axial dimension X of the axially extending cam segment 80. Preferably these dimensions vary in a binary arithmatic sequence such as l, 2, 4, 8 and 16 so that as will be described below they may be selectively combined to present collectively a total axial dimen- Each of the discs 60 is formed with a plain bore accommodating the arm shaft 25. One side of each freely journaled disc 60, as shown in FIG. 4A, is formed with an axially projecting hub 91 from which a stop projection 92 extends radially and is formed with a radial inner stop abutment surface 93.

Substantially diametrically opposite the inner stop abutment surface 93, an outer stop abutment surface 94 is provided on an arcuate lug 95 projecting axially from the face 96 of the freely joumaled disc. As shown in FIGS. 5 to 9, a radial clear space is provided between the outside of the inner stop abutment surface 93 and the inside of the outer stop abutment surface 94.

As shown in FIG. 4B, the opposite side of each freely journaled disc 60 is formed with an axially projecting cam follower block 97 disposed adjacent to the bore 90 for cooperation with one of the cam segments 80. The cam follower blocks 97 one on each disc are preferably of an equal dimension axially of the discs and preferably that axial dimension is at least as large as the largest axial dimension X of cam segment 80.

Referring to FIGS. 1, 6, 6A, 8 and 8A there is provided in cooperation with each adjacent pair of keyed and freely journaled discs an interrupter element 100. Since all of the interrupter elements are identical one will now be described in detail.

Each interrupter element is formed with a substantially flat base portion 101 formed with a circular opening 102 adapted loosely to embrace a circular armature rod 103 of a conventional electromagnetically influenced solenoid indicated generally at 104. Preferably, the solenoid includes a coil 105 arranged between the upturned arms 106 of a U-shaped frame 107 transversely of which said armature rod is shiftable. A head 108 formed on the armature rod 103 constrains the interrupter base portion on the rod. Extending upwardly from the base portion 101, the interrupter element is formed with an arched portion 109 which terminates in a head arranged substantially in alignment with the flat base portion. The head includes a control lug 110 extending on one side and a stop lug extending on the other side thereof.

A coil spring 121 stretched between the arched portion 109 of the interrupter and the solenoid frame 107 serves to pivot the interrupter element about the upper edge of the solenoid frame arm 106 when the solenoid is deenergized and when the inner cam surface 75 of the control cam groove 74 permits as shown in FIG. 6

causing the interrupterelement to shift radially inwardly with respect to the discs 50 and 60. A leaf spring 122 secured as by welding to the arched portion 109 of the interrupter element and bearing against the solenoid rod head 108 constrains the solenoid rod from being completely withdrawn from the coil 105.

When the solenoid coil is energized, the armature rod 103 is drawn toward the coil and the interrupter element is biased so as to turn into the position shown in FIG. 8 when the outer cam surface 76 of the control cam groove 74 permits.

The soleniod frames 107 may all be mounted on a common support block 123 which is secured in the sewing machine bracket arm beneath the arm shaft. Each of the interrupter elements 100 is connected to its respective solenoid armature rod by a simple swivel joint providing capacity for pivotal movement not only to accommodate shifting movement of the interrupter elements radially of the discs, but also for limited movement of the interrupter heads in a direction axially along the stack of discs.

It will be understood that the adder mechanism, as illustrated in FIG. 1, comprises a plurality of sets of keyed and freely joumaled discs 50 and 60, respectively, each set being effective to add or subtract a given increment X from the total axial dimension of the assembled stack corresponding to the axial dimension X of the cam segment 80 which is included in that set. Each unit or set comprises four disc sides, i.e., both sides of a keyed and both sides of a freely journaled disc, but it must be kept in mind that the four sides required to complete each set need not necessarily be carried on the same two discs. In order to accommodate the particular interrupter construction illustrated,

it is necessary that the four disc sides of each set comprise the sides of three adjacent discs; i.e., both sides of one freely journaled disc and one side of each of the keyed discs on each side thereof. As shown in FIG. 1,

therefore, there are five sets utilizing eleven discs.

The operation of one typical set of discs in adding and subtracting the increment X of axial dimension to the stack of discs will now be described on the particular reference to FIGS. 5 to 9.

In FIGS. 5 to 9 the positionsof the control lug 110 and of the stop lug 120 on the interrupter element are superimposed. FIG. 4 illustrates the relative position of keyed and freely joumaled discs in a set while the solenoid corresponding thereto has been energized resulting in an overlap of the cam segment 80 and follower block 97 so that the increment X is added to the stack dimension. As long as the solenoid controlling the interrupter element remains energized, the control lug 110 will continue to track the outer cam surface 76 of the control groove 74 in the keyed disc 50 and the system will remain unchanged with both discs 50 and 60 coupled together frictionally and turning with the shaft because of the key 73 on the disc 50.

The preferential time for a change in the actuation of the solenoid 104 occurs when the control lug 110 occupies the narrow portion 77 of the control cam groove 74 since then no immediate motion of the interrupter will occur and noise and vibration will be minimized. If the solenoid 104 is deenergized in the position of parts shown in FIG. 5, the control lug will then track the inner cam surface 75. With the shaft 25 turning clockwise, as viewed in FIGS. 5-9, 180 of shaft rotation will transpire until the stop lug 120 contacts the inner stop surface 93 on the freely joumaled disc 60.

During the succeeding approximately 180 of shaft rotation from the position shown in FIG. 6 to that shown in FIG. 7, the stop lug 120 will engage the inner stop surface 93 and constrain the freely joumaled disc 60 from rotation thus changing the relative angular po sitions of the discs 50 and 60 and shifting the follower block 97 out of engagement with the cam segment 80 and against the face 82 of the keyed disc. The increment X equal to the axial dimension of the cam seg ment 80 will thus be subtracted from the total axial dimension of the stack.

Thereafter, as long as the solenoid 104 remains deenergized, the control lug 110 will continue to track the inner cam surface 75 of the contfol groove 74 and no further change will occur as to the angular relationship between the discs 50 and 60 because the cam groove 74 will continue to shift the stop lug 120 clear of the abutment 93 during each revolution of the shaft.

Again the preferential time for a change in the actuation of the solenoid occurs when the control lug 110 occupies the narrow portion 77 of the control cam broove 74 in the position of parts shown in FIG. 7. If in this position of parts the solenoid 104 is energized, the control lug 110 will thereafter track the outer cam surface 76 of the control groove 74 and after 180 of shaft rotation the stop lug 120 will engage the outer stop abutment surface 94 as shown in FIG. 8. During the subsequent approximately 180 of shaft rotation, the stop lug 120 will continue to engage the abutment surface 94 to constrain the freely journaled disc from rotation. A change in the relative angular positions of the keyed and freely joumaled discs and will occur causing the follower block 97 to ride up the ramp 81 on to the axial cam segment thus to add the increment X to the total dimension of the stack of discs as shown in FIG. 9, which incidentally corresponds to the position of parts shown in FIG. 5 indicating the completion of a cycle of changes.

The disc positions in which an increment X is added and in which an increment X is subtracted from the total axial dimension of the stack is shown in FIG. 2. Where the axial cam segment 80 and camfollower 97 are shifted into engagement, the axial dimension of the cam segment 80 is added as indicated by +X. where the axial cam segment 80 and the cam follower 97 are shifted out of engagement, the cam follower 97 abuts the keyed disc face 82 and the axial dimension of the cam segment 80 is subtracted as indicated by X.

It will be appreciated that the sets of the keyed and freely journaled discs, each with an individual solenoid controlled interrupter may be controlled individually by selective actuation of the solenoid thereof to add or subtract the axial increment represented by the dimension of the respective cam segments 80 from the collective axial dimension of the stack. The solenoids may be activated selectively by any known system or arrangement, such system not forming a direct part of this invention.

Preferably, that set of discs which includes the fixed keyed disc 50 will carry a cam segment 80 with the smallest axial dimension X and the other sets will be arranged in an order from the fixed keyed disc in proportion to the magnitude of the axial dimension X. By this arrangement, the interrupters will be moved sideways the least amount during the operation of the adder mechanism.

As disclosed with reference to the above description and illustrated in the drawings, an abundance of time is available with this invention for introduction of a pattern signal and for manipulation of the actuator in response thereto. This actuator is, therefore, particularly well adapted for faithful operation at high speeds. When a pattern signal in the form of a change in the electrical activation of one or more of the solenoids l04 is initiated at the most preferential time, one-half revolution of the drive shaft is available for response by the interrupter element 100 to this change of solenoid actuation. The response by the adder mechanism to this input of pattern signal then takes place gradually over the greater part of the next succeeding half revolution of the drive shaft so that almost one complete revolution of the drive shaft is available for the processing of the pattern information for each successive stitch. As a result, the time requirements for input of pattern information are not critical and minimum limitation is imposed by this adder mechanism on the speed of sew ing machine operation.

It will also be apparent from the above description of the operation that this adder mechanism responds only to changes in pattern information. In the intervals between changes, the discs simply rotate in unison. In contrast with other known adding mechanism which automatically return to a base point or zero setting after each repetitive cycle of operation, the present adder mechanism is advantageous in that the wear incident to machine operation is greatly reduced. The present adder mechanism, however, retains the advantage usually present in return to zero systems that the response to any pattern signal will always reflect an absolute relationship with a base point or zero of the system.

With reference to FIGS. 6 and 8, it will be apparent that when the stop lug 120 of any interrupter element is engaged with a stop abutment surface 93 or 94, any force applied to the interrupter element by the stop abutments will act in a direction substantially perpendicular to the solenoid armature rod 102 on which the interrupter element is swiveled. Such forces applied by the stop abutments will occur incident to the output of the adder mechanism and will vary considerably according to the .work which the adder mechanism must perform. These forces will be derived from the arm shaft and not from the solenoids 104 or springs 121. The control forces acting to shift the interrupter element radially inwardly or outwardly of the discs, which forces are applied to the interrupter element by the solenoid rod head 108 or by the coil spring 121, therefore, will act substantially perpendicular to the direction of any forces acting on the interrupter element incident to the output of the adder. As a result, the required size of the solenoid coils 105 and the size of the springs 121 may be minimized. Moreover, since the control actuators need not respond to forces incident to varying magnitudes of output, the same design may be used for a wide variety of installations involving widely different output force requirements.

Having set forth the nature of this invention, what is claimed herein is:

1. A rotary adder mechanism comprising a frame, a rotary drive shaft journaled in said frame, a plurality of discs stacked coaxially on said drive shaft, at least one of said discs being keyed to said drive shaft to rotate in synchronism therewith, and at least one of said discs being freely journaled on said drive shaft, means for frictionally coupling said keyed and freely journaled discs for rotation together, interengageable axial cam segments formed on adjacent keyed and freely journaled discs for movement into and out of engagement responsive to relative angular movement of said keyed and freely journaled discs, output means responsive to the total axial dimension of said plurality of said stacked discs, and control means carried on said frame for selectively preventing rotation of said freely journaled disc relative to said keyed disc to impart relative angular movement to said keyed and freely journaled discs.

2. A rotary adder mechanism as set forth in claim 1 in which said control means includes stop abutment means formed on said freely journaled discs, and an interrupter element carried by 'said frame and shiftable into and out of blocking engagement with said stop abutment means i 3. A rotary adder mechanism as set forth in claim 2 in which means are provided responsive to a signal generated externally of said adder mechanism for shifting said interrupter element into blocking engagement with said stop abutment means, and in which means are provided on said keyed disc for automatically shifting said interrupted element out of blocking engagement with said stop abutment means.

4. A rotary adder mechanism as set forth in claim 3 in which two stop abutments are provided on said freely journaled disc, in which said means for shifting said interrupter element into blocking engagement with said stop abutment means is responsive to two different signals generated externally of said adder mechanism for selectively shifting said interrupter element into blocking engagement with either of said two stop abutments, and in which said means on said keyed disc for automatically shifting said interrupter element out of blocking engagement with said stop abutment means is arranged to effect that relative angular position between said keyed and freely rotatable discs in which said axial cam segments are in engagement after one of said stop abutments has been engaged by said interrupter element, and arranged to effect that relative angular position of said keyed and freely rotatable discs in which said axial cam segments are out of engagement after the other of said stop abutments has been engaged by said interrupter element. 1

5. A rotary adder mechainsm as set forth in claim 1 in which a plurality of sets of interengageable axial cam segments are provided, each set being carried on a separate pair of adjacent keyed and freely journaled discs.

6. A rotary adder mechanism as set forth in claim 5 in which each set of interengageable axial cam segments is individually regulated by a separate one of said control means, and in which said output means is responsive to the total axial dimension of the discs stacked on said drive shaft as influenced by said axial cam segments collectively.

7. A rotary adder mechanism as set forth in claim 6 in which the cam segments of each set contribute to dimensional change axially of the stack which differ one from the other in a binary arithmatic sequence.

8. A rotary adder mechanism as set forth in claim 3 in which said means responsive to a signal generated externally of said adder mechanism for shifting said interrupter element into blocking engagement with said stop abutment means conprises an electromagnetic actuator responsive to electric pattern signals to shift said interrupter element in one direction, and in which said means on said keyed disc for automatically shifting said interrupter element out of blocking engagement with said stop abutment means comprises a control cam surface formed on said keyed disc.

9. A rotary adde'r mechanism as set forth in claim 4 in which said means for shifting said interrupter element into blocking engagement with said stop abutment means comprises an electromagnetic actuator effective to shift said interrupter element in one direction in response to a signal comprising the presence of an electric potential applied to said electromagnetic and spring means effective to shift said interrupter element in the opposite direction in response to a signal comprising the absence of an electric potential applied to such electromagnet, and in which said means on said keyed disc for automatically shifting said interrupter element out of blocking relation with said stop abutment means comprises a first control cam surface engageable with said interrupter element when said interrupter element is under the influence of said electromagnetic actuator, and a second control cam surface engageable with said interrupter element when said interrupter element is under the influence of said spring means.

10. An adder mechanism comprising a circularly moving drive shaft, a first disc drivingly engaged with said drive shaft for circular movement in synchronism therewith, a second disc arranged adjacent to said first disc and freely journaled on said drive shaft, an interrupted element arranged alongside said discs and formed with a stop lug and control lug, a pair of angularly spaced stop abutments carried on said second disc, said stop abutments being located in suffciently different radial positions on said second disc so as to accommodate said interrupter element stop lug in the radial clearance space therebetween, said first disc being formed with control cam surfaces tracked by said interrupter element control lug, said control cam surfaces including one segment constraining said control lug in a position in which said stop lug occupies the radial clearance space between said stop abutments on said second disc, and said control cam surface including another segment in which said control lug is free to be moved selectively into the path of either of said stop abutments, means for shifting said interrupter element stop lug selectively into the path of one of said stop abutments including means for applying a control force to said interrupter element in a direction substantially perpendicular to the control cam surface tracked by the control lug, means for supporting said interrupter element at a location such that forces incident to engagement of said stop lug with said stop abutment are transmitted to said supporting means for said interrupter element in a direction substantially perpendicular to the direction of application of said control forces, and interengageable axially extending cam segments formed on said adjacent first and second discs for varying the total axial dimension of said assembled discs in response to changes in the angular orientation of said adjacent discs on said drive shaft. 

1. A rotary adder mechanism comprising a frame, a rotary drive shaft journaled in said frame, a plurality of discs stacked coaxially on said drive shaft, at least one of said discs being keyed to said drive shaft to rotate in synchronism therewith, and at least one of said discs being freely journaled on said drive shaft, means for frictionally coupling said keyed and freely journaled discs for rotation together, interengageable axial cam segments formed on adjacent keyed and freely journaled discs for movement into and out of engagement responsive to relative angular movement of said keyed and freely journaled discs, output means responsive to the total axial dimension of said plurality of said stacked discs, and control means carried on said frame for selectively preventing rotation of said freely journaled disc relative to said keyed disc to impart relative angular movement to said keyed and freely journaled discs.
 2. A rotary adder mechanism as set forth in claim 1 in which said control means includes stop abutment means formed on said freely journaled discs, and an interrupter element carried by said frame and shiftable into and out of blocking engagement with said stop abutment means.
 3. A rotary adder mechanism as set forth in claim 2 in which means are provided responsive to a signal generated externally of said adder mechanism for shifting said interrupter element into blocking engagement with said stop abutment means, and in which means are provided on said keyed disc for automatically shifting said interrupted element out of blocking engagement with said stop abutment means.
 4. A rotary adder mechanism as set forth in claim 3 in which two stop abutments are provided on said freely journaled disc, in which said means for shifting said interrupter element into blocking engagement with said stop abutment means is responsive to two different signals generated externally of said adder mechanism for selectively shifting said interrupter element into blocking engagement with either of said two stop abutments, and in which said means on said keyed disc for automatically shifting said interrupter element out of blocking engagement with said stop abutment means is arranged to effect that relative angular position between said keyed and freely rotatable discs in which said axial cam segments are in engagement after one of said stop abutments has been engaged by said interrupter element, and arranged to effect that relative angular position of said keyed and freely rotatable discs in which said axial cam segments are out of engagement after the other of said stop abutments has been engaged by said interrupter element.
 5. A rotary adder mechainsm as set forth in claim 1 in which a plurality of sets of interengageable axial cam segments are provided, each set being carried on a separate pair of adjacent keyed and freely journaled discs.
 6. A rotary adder mechanism as set forth in claim 5 in which each set of interengageable axial cam segments is individually regulated by a separate one of said control means, and in which said output means is responsive to the total axial dimension of the discs stacked on said drive shaft as influenced by said axial cam segments collectively.
 7. A rotary adder mechanism as set forth in claim 6 in which the cam segments of each set contribute to dimensional change axially of the stack which differ one from the other in a binary arithmatic sequence.
 8. A rotary adder mechanism as set forth in claim 3 in which said means responsive to a signal generated externally of said adder mechanism for shifting said interrupter element into blocking engagement with said stop abutment means conprises an electromagnetic actuator responsive to electric pattern signals to shift said interrupter element in one direction, and in which said means on said keyed disc for automaticalLy shifting said interrupter element out of blocking engagement with said stop abutment means comprises a control cam surface formed on said keyed disc.
 9. A rotary adder mechanism as set forth in claim 4 in which said means for shifting said interrupter element into blocking engagement with said stop abutment means comprises an electromagnetic actuator effective to shift said interrupter element in one direction in response to a signal comprising the presence of an electric potential applied to said electromagnetic and spring means effective to shift said interrupter element in the opposite direction in response to a signal comprising the absence of an electric potential applied to such electromagnet, and in which said means on said keyed disc for automatically shifting said interrupter element out of blocking relation with said stop abutment means comprises a first control cam surface engageable with said interrupter element when said interrupter element is under the influence of said electromagnetic actuator, and a second control cam surface engageable with said interrupter element when said interrupter element is under the influence of said spring means.
 10. An adder mechanism comprising a circularly moving drive shaft, a first disc drivingly engaged with said drive shaft for circular movement in synchronism therewith, a second disc arranged adjacent to said first disc and freely journaled on said drive shaft, an interrupted element arranged alongside said discs and formed with a stop lug and control lug, a pair of angularly spaced stop abutments carried on said second disc, said stop abutments being located in suffciently different radial positions on said second disc so as to accommodate said interrupter element stop lug in the radial clearance space therebetween, said first disc being formed with control cam surfaces tracked by said interrupter element control lug, said control cam surfaces including one segment constraining said control lug in a position in which said stop lug occupies the radial clearance space between said stop abutments on said second disc, and said control cam surface including another segment in which said control lug is free to be moved selectively into the path of either of said stop abutments, means for shifting said interrupter element stop lug selectively into the path of one of said stop abutments including means for applying a control force to said interrupter element in a direction substantially perpendicular to the control cam surface tracked by the control lug, means for supporting said interrupter element at a location such that forces incident to engagement of said stop lug with said stop abutment are transmitted to said supporting means for said interrupter element in a direction substantially perpendicular to the direction of application of said control forces, and interengageable axially extending cam segments formed on said adjacent first and second discs for varying the total axial dimension of said assembled discs in response to changes in the angular orientation of said adjacent discs on said drive shaft. 